CL_PLATFORM_NOT_FOUND_KHR (-1001) while using docker ubuntu22.04 image with GPU enabled.

[hungpham3112]

Hi, I'm new to heterogeneous programming with OpenCL. Today, I'm trying to create workspace using docker image ubuntu22.04 for OpenCL development.

Firstly, I run docker image with GPU enable via --gpus all flag:
docker run --gpus all -it my_container ubuntu:22.04

then I downloaded all the header file (/usr/include/CL/) and ICD (Installable Client Driver) which located in /usr/lib/x86_64-linux-gnu/libOpenCL.so

my toy program main.c in OpenCL:

#define CL_TARGET_OPENCL_VERSION 300

#include <stdio.h>
#include <CL/cl.h>

int main() {
	cl_device_id my_device_id;
	int result;
	clGetDeviceIDs(
		NULL,
		CL_DEVICE_TYPE_GPU,
		1,
		&my_device_id,
		NULL
	);
	if (result != CL_SUCCESS) {
		printf("Something went wrong\n");
		return 1;
	} else {
		printf("Good");
	}

}

I compiled with gcc main.c -o ./main -lOpenCL, output: clGetPlatformIDs(-1001)

What am I missing in here? How can I develop workflow for OpenCL in docker, I see cuda/opencl image but it seems not maintain anymore.

Edit: After an hour of searching I found that I missed the package called pocl-opencl-icd. Just simply sudo apt install pocl-opencl-icd, now clinfo show it found 1 platform but not CUDA platform in docker env.

Question: What is the relationship between Pocl and OpenCL. Why include pocl in docker container make clinfo can detect platform but in the "normal" environment, I mean the host OS not docker container, I don't need to download pocl-opencl-icd so clinfo still be able to detect platform? What is the different in here? Please enlighten me.